Special package



Oct. 19, 1965 Original Filed July 20, 1960 INVENTORS ROBERT L. DREYFUSWYLIE C. KIRKPATRICK ATTORNEY United States Patent SPECIAL PACKAGERobert L. Dreyfus, Greenville, S.C., and Wylie C. Kirkpatrick,Greenwich, Conn, assignors to W. R. Grace & Co., Duncan, S.C., acorporation of Connecticut Original application July 20, 1960, Ser. No.44,196, now Patent No. 3,095,677, dated July 2, 1963. Divided and thisapplication May 14, 1963, Ser. No. 280,464

2 Claims. (Cl. 206-65) This application is a division of applicationSerial Number 44,196, filed July 20, 1960, now US. Patent 3,095,677,granted July 2, 1963.

This invention relates to packaging and more particularly to a novelmethod of packaging employing shrinkable material and to the packageresulting therefrom.

Packaging of small inexpensive items has long posed a problem for thepackaging industry. It is essential that packaging costs for such itemsto kept to an absolute minimum else the packaging cost may equal orexceed the value of the item being packaged. Because of the difficultyin lowering such packaging costs it is not uncommon to handle smallitems in unpackaged bulk quantities or as an alternative to package anumber of the items in a single package. Both attempts to circumvent theheretofore high cost of packaging have not been satisfactory for obviousreasons. Whatis needed therefore is a low cost package which can beproduced with a minimum of labor, machinery and materials.

Accordingly, it is an object of the present invention to provide a novelmethod of packaging employing shrinkable materials.

Another object is to provide a novel method of packaging which issuitable for small, low cost items.

It is a further object to provide a novel method for packaging smallobjects continuously in a continuous strip of material.

A further object is to provide a novel method of packaging small,irregular-shaped objects and also fragile and heat-sensitive objects.

Another object is to provide a package which is low in cost and suitablefor small items.

Other and further objects, advantages and features of the presentinvention will become apparent to those skilled in the art from thefollowing description taken in conjunction with the accompanyingdrawings in which:

FIGURE 1 is a top plan view of a strip of shrinkable films havingobjects spaced at regular intervals upon said strip.

FIGURE 2 is a top plan view of the strip showing the film in itsshrunken state and the objects enclosed within the shrunken film strip.

FIGURE 3 is a partial cross-sectional view of FIGURE 2 along the line33.

FIGURE 4 is an elevational view partially in section showing theformation of a pocket in a strip of film and the packaging of anirregularly shaped object in said pocket.

The plastic age has produced many new materials possessing propertiesthat make them particularly useful in the field of packaging. One hasonly to look about to see the great use of transparent materials inpackaging made possible by the development of inexpensive transparentmaterials. With the development of thermoplastics, it has becomepossible to mold containers in various shapes and styles. Shrinkableplastic materials have also made it possible to obtain skin-tightpackage coverings. This invention makes use of shrinkable materials in anovel manner to produce a novel package which solves a problem oflong-standing in the industry.

The preferred shrinkable material and that used in the 3,212,635Patented Oct. 19, 1965 examples is a heat shrinkable, irradiated,biaxially oriented polyethylene film, specifically Alathon 14, averagemolecular weight 20,000, density 0.914 and having a melt index of 1.8which has been irradiated to an extent of about 12 megarad and thenbiaxally stretched 350% in both a lateral and longitudinal direction.The irradiated, biaxially oriented polyethylene film has a shrink energyof about 150 psi in both directions at 96 C.

There may also be employed in this invention shrinkable irradiatedpolyethylene films which have been irradiated to an extent of 2 to 100megarads, preferably 6 to 20 megarads. The irradiation may beaccomplished in conventional fashion, e.g. by the use of electron beamgenerators such as the 2,000,000 volt General Electric resonanttransformer unit, or high energy particle generators of 50,000 to50,000,000 volts or a Van de Graaff electron generator such as thatwhich operates at 2,000,000 volts with a power output of 500 watts,manufactured by the High Voltage Engineering Corp., Burlington, Mass. Inaddition to the use of electrons for irradiating the polyethylene therecan be employed other sources of radiation which are capable ofproducing beta or gamma rays. There can be employed any of theirradiation procedures disclosed in Baird et al. application Serial No.713,848, filed February 7, 1958 (now US. Patent 3,022,543), or RainerPatent 2,877,500. The disclosures of the Baird et al. application andthe Rainer patent are hereby incorporated by reference.

Orientation of the film may be accomplished by monoaxi-al or biaxialstretching. It is possible to stretch irradiated polyethylene from 100%to 700% longitudinally and from 100% to 900% laterally. Biaxialorientation results from the simultaneous radial and longitudinalstretching of the polyethylene. One method of biaxially orientingpolyethylene is to force air into a heated tube of polyethylene forminga bubble which is trapped between two sets of pinch rolls. The tube ofpolyethylene undergoes a radial and longitudinal stretch to accommodatethe air bubble. This process is described in more detail in the Baird etal. application Serial No. 713,848.

The biaxially oriented polyethylene prepared by the above procedures hasa high shrink energy, e.g. 100 to 500 psi. at 96 C. Shrink energy is theforce of contraction at a given temperature when the material isrestrained and more specifically it is the measurable tension in a fullymonodirectionally restrained strip of film when heated to the specifiedtemperature.

As a starting polyethylene there may be employed high, medium or lowdensity polyethylene prepared by high or low pressure techniques andhaving molecular weights from 7000 to 35,000 or even higher.

In place of irradiated polyethylene there can also be employed in myinvention irradiated, solid copolymers of ethylene and propylene (e.g.,a 5050 copolymer) or irradiated solid copolymers of ethylene with aminor amount, e.g. 5% of isobutylene, amylene, acetylene, butadiene,butene-l and butene-2, or irradiated blends of low density polyethylenewith from 25 to by weight of a copolymer of ethylene and from 0.5 to 15%by weight of another olefin which has 3 to 18 carbon atoms, or blockcopolymers of polyethylene with a minor amount, e.g., 5% ofpolyisobutylene, and irradiated graft polymers of polyethylene orpolypropylene with monomers such as acetylene, butadiene, butylene,ethylene or polypropylene which materials are biaxially oriented. Therecan also be employed solid polypropylene and polyvinyl chloride whichare biaxially oriented. It is possible to employ other film materialshaving a high degree of shrink and which do not decompose or melt underthe temperature required to shrink such materials.

Referring now more particularly to FIGURE 1, the numeral refers to astrip of irradiated, biaxially oriented polyethylene film which isapproximately 1 mil thick 6 inches wide and 24inches long. The strip offilm is placed upon a suitable flat supporting surface not shown in thedrawings. There is placed upon the film strip a plurality of smallrounded objects approximately 1 inch in diameter and A inch in height,e.g. buttons. The objects are spaced along the center of the film stripapproximately 4 inches apart and from 4 to 6 inches from either end ofthe film strip.

A hot air blower capable of generating a gas temperature ofapproximately 300 to 750 F. is placed above the strip of film and thehot air is directed against the top surface of the film bearing theobjects. Starting at one end of the film strip the jet of hot air ismoved along the film strip at a speed which will permit the exposedsurface of the film to be almost completely shrunk.

In the present example the film will shrink approximately 75% of itsoriginal dimensions. As the film shrinks it will be observed that thefilm in the immediate vicinity of the objects curls over and around eachobject, thereby partially encapsulating the object within the strip offilm. The shrunken strip of film with the partially encapsulated objectsis shown in FIGURE 2 wherein 14- refers to the area over the object 11which is not covered by the film and refers to the outline of theunshrunk film pocket surrounding the object. The shrunken film is nowapproximately 15 mils thick. FIGURE 3 shows in detail the manner inwhich the thickened shrunk film has partially closed over the object andalso shows the unshrunk portion of the film 13 directly under the objectwhich is substantially uniform in guage of thickness and has retainedits original thickness of 1 mil.

The above procedure permits the packaging of objects in a transparentstrip of plastic material by merely placing the objects to be packagedupon a strip of shrinkable film and then applying heat. The applicationof heat is sufficient to cause the object to be encapsulated within theshrunken film. No wrapping step is required to bring the film over theobject.

This invention also contemplates the continuous encapsulation of objectswithin a strip of material. For example, a polyethylene film strip couldbe continually dispensed from a roll toward a pull roll system or onto amoving conveyor, whereupon the products to be packaged would beautomatically placed upon the strip of film and moved towards a heatsource which would shrink the film and encapsulate the product. Thepackaged product could then be taken up on rolls or cut in lengths orhandled in any manner desired. In employing such a continuous orautomatic procedure it is possible and might be desirable to indent theobjects into the film prior to its being shrunk in order to insure moreuniform and precise encapsulation. This could be accomplished by placingthe object on the film with some degree of force while the film is abovea resilient base. Another method of insuring a more uniformencapsulation would be to employ a conveyor belt having a series ofpockets spaced along the belt. As the film moves along the belt theobject being packaged is placed upon the film so as to fit into thepocket. The object is held securely in place through the shrinkingoperation. It might also be necessary in certain cases to provide a moreuniform and attractive end product to employ guides to prevent the filmedges from curling while exposed to heat.

While a hot air gun is an obvious source of heat for shrinking the film,it is obvious that other heat sources could be employed and that anytemperature that is high enough to shrink the film without melting ordecomposing the film will be satisfactory.

There are many possible alternative methods of mere chandising objectspackaged according to this invention. The packaged product could bewound on rolls and the desired quantity could be cut off in a continuousstrip. It is also possible to cut the packaged product into strips ofdifferent sizes or even into individual units. The thickened film issufficiently sturdy so that the strips may be displayed by hanging fromsome suitable support. The resulting package is sturdy, transparent andattractive.

The invention is particularly suitable for packaging objects which haverelatively fiat regular shapes and are not sensitive to the temperaturesemployed in shrinking the film. Thus there may be packaged such objectsas buttons, coins, washers, medals, chips, tablets, pills, discs, etc.It is necessary that the object be sufiiciently rigid so as not todeform under the strain of the shrinking film. This invention is notlimited, however, to objects having rounded shapes but also applies toobjects having other geometric configurations, e.g. rectangles,triangles, etc. With the shrinkable materials disclosed in thisapplication, it is possible to encapsulate objects up to /2 inch inthickness.

Taller and thicker objects than the aforementioned can be suitablypartially encapsulated or held to a film strip if such objects have arelatively thin extension, projection or flange at the base thereof overwhich the film may curl when shrinking, e.g., transformers or othersmall electrical parts which have thin lateral projections which serveto retain fastening devices.

By modifying the above-described encapsulation process it becomespossible to encapsulate delicate, heat-sensitive or irregular-shapedobjects. Flat forms, e.g. metal washers, are placed upon a strip ofirradiated, biaxially oriented polyethylene film which is shrunk by theapplication of heat in the manner heretofore described. The forms areeasily removed from their pockets within the shrunken film because ofthe resiliency and elasticity of the film. The delicate, heat sensitive,irregular shaped or any other object of suitable size may then be placedwithin the pockets of unshrunken film which will then hold the object.If a tighter pocket is desired, heat may be applied to the unshrunkpocket causing it to shrink and tighten about the object containedtherein.

FIGURE 4 discloses a strip of irradiated, biaxially orientedpolyethylene film 20 which has been shrunk about flat round forms 21 andfrom which the forms have been removed leaving empty pockets 22 ofunshrunk film. There have been placed in several of theempty unshrunkpockets objects 23, such as brass screws, which are retained thereinbecause of the narrow opening of the pocket. If desired the unshrunkpocket may be shrunk about the enclosed brass screw by the applicationof heat.

The invention described in detail in the foregoing specification issusceptible to changes and modifications as may occur to persons skilledin the art without departing from the principle and spirit thereof. Theterminology used in the specification is for purpose of description andnot of limitation, the scope of the invention being defined in theclaims.

We claim:

1. A package comprising a strip of shrunken film containing at least onepocket of unshrunken film integral with said strip and extending belowand strip, and having an object partially enclosed within said pocket bythe shrunken film at the edge of the pocket being curled over the upperedge of said object.

2. The package of claim 1 within said strip contains a plurality ofpockets.

References Cited by the Examiner UNITED STATES PATENTS 2,491,423 12/49Snyder 20678 2,861,405 11/58 Hanford 20678 2,903,139 9/59 Penman.

2,975,931 3/61 Harrison.

3,034,271 3/62 Carpenter.

3,060,655 10/62 Dreyfus.

3,095,084 6/63 White 20683 LOUIS G. MANCENE, Primary Examiner. THERON E.CONDON, Examiner.

1. A PACKAGE COMPRISING A STRIP OF SHRUNKEN FILM CONTAINING AT LEAST ONE POCKET OF UNSHRUNKEN FILM INTERGRAL WITH SAID STRIP AND EXTENDING BELOW AND STRIP AND HAVING AN OBJECT PARTIALLY ENCLOSED WITHIN SAID POCKET BY THR SHRUNKEN FILM AT THE EDGE OF THE POCKET BEING CURLED OVER THE UPPER EDGE OF SAID OBJECT. 